1. Field of the Invention
The present invention relates to a noise absorber and a case for a noise absorber.
2. Discussion of Background
Numerous noise absorbers fulfilling similar noise absorbing functions have been proposed and put into practical use to date. One of the well-known noise absorbers employs an insulating resin to securely mold a magnetic core onto a cable. This noise absorber is, however, not user-friendly since in order to mount the noise absorber onto a cable, implementation of a burdensome and expensive molding process is necessary.
Noise absorbers which employ split ferrite cores disposed in a holding case that comprises two case members connected by a hinge and secured by a means for interlocking are disclosed in, for example, U.S. Pat. Nos. 4,825,185 and 4,885,559. The hinge and the means for interlocking are situated so as to face each other at external circumferencial surfaces of the holding case. The split ferrite cores are in close contact with each other by taking advantage of a resiliency that manifests when the case members are secured so that a substantially closed, cylindrical magnetic circuit is achieved.
However, with the noise absorbers described above, the resiliency, manifesting itself when the case members are secured, is applied to both the hinge and the means for interlocking. Thus, when these noise absorbers are used over a substantial period, the mechanical strength of the hinge and the means for interlocking deteriorates, eventually resulting in a partial or complete separation of the case members.
Moreover, since these noise absorbers employ split ferrite cores, when the mechanical strength of the hinge and the means for interlocking deteriorates, a gap appears between the split ferrite cores, diminishing the noise absorbing characteristics.
Also, since the means for interlocking is situated at the exterior of the holding case, additional mounting space is required to accommodate projections of the means for interlocking and this is particularly disadvantageous when space for installing the noise absorber is limited.
In another example of the prior art technology, Japanese Unexamined Utility Model Publication No. 60117/1994 discloses a noise absorber that employs a single cylindrical magnetic core enclosed by two separate case members. The cable onto which the noise absorber is to be mounted, is inserted through the cylindrical magnetic core after which it is wound around the cylindrical magnetic core once. One of the two case members has indented portions while the other of the two case members has projections that face opposite the indented portions. The two case members are secured by interlocking the projections with the indented portions.
In this example, the end user is supplied with a noise absorber of which a cylindrical magnetic core is enclosed by secured case members, so the two case members have to be separated from each other in order to remove the cylindrical magnetic core, insert and wind the cable around the cylindrical magnetic core and then reassemble the two case members. This imposes an extremely troublesome burden on the end user.
It is an object of the present invention to provide a noise absorber and a case for a noise absorber that reduce the load placed upon the hinge arrangement and the means for interlocking.
It is a further object of the present invention to provide a noise absorber and a case for a noise absorber being compact and possible to mount on a cable where mounting space is limited.
It is a still further object of the present invention to provide a noise absorber and a case for a noise absorber being easy to assemble and easy to attach to a cable.
In order to achieve the objects described above, the present invention discloses a noise absorber and a case for a noise absorber in two modes.
The case in the first mode according to the present invention comprises a first case member, a second case member, a means for interlocking and a hinge arrangement.
The first case member has two opposite sides and includes a first cable guide at one of the two opposite sides of the first case member and a second cable guide at another of the two opposite sides of the first case member, with a first core housing provided between the opposite sides of the first case member. The second case member has two opposite sides and includes a third cable guide at one of the two opposite sides of the second case member and a fourth cable guide at another of the two opposite sides of the second case member, with a second core housing provided between the opposite sides of the second case member.
The means for interlocking secures the first case member and the second case member, and the hinge arrangement movably connects one of the opposite sides of the first case member with one of the opposite sides of the second case member.
The case in the first mode according to the present invention comprises first and second case members each including a core housing. This structure allows a magnetic core to be housed entirely in said case by housing half of the magnetic core inside the first core housing of the first case member and housing the other half of the magnetic core into the second core housing of the second case member and by closing the first and second case members together. Thus, the case, used in combination with a magnetic core, constitutes the noise absorption apparatus.
The noise absorber of the present invention can be mounted on a cable of an electronic device to absorb noise generated inside or outside the electronic device by guiding the cable through apertures formed by the first and fourth cable guides and the second and third cable guides, and the cable through passage of the magnetic core, thereby facilitating the cable insertion process.
In addition, the case is secured by the means for interlocking after a cable is passed through the cable through passage of the magnetic core, so that resin molding becomes unnecessary, thereby enabling the end user to mount the noise absorber on a cable.
Moreover, the first and second case members are movably connected by a hinge arrangement on one side of the case and secured by the means for interlocking at the other side of the case, so the main function that the hinge arrangement and the means for interlocking must fulfill is holding the magnetic core. Thus, the load placed on the hinge arrangement and the means for interlocking is greatly reduced.
Therefore, the case and noise absorber according to the present invention are much different from the case and noise absorber disclosed in the prior art, in which a pair of split ferrite cores are placed in close contact with each other by using the resiliency of the case.
Furthermore, when the first and second case members are secured, the hinge arrangement projects out in the lengthwise direction of the case which conforms with the direction of the cable, so that the external dimension of the noise absorber according to the present invention is less than that of the noise absorber disclosed in the prior art. While the external dimension of the case increases by the distance over which the hinge arrangement projects out, this increase does not present any problem, since the cable extends out at two sides in the lengthwise direction of the case.
The case in the second mode according to the present invention comprises a first case member, a second case member, a first means for interlocking and a second means for interlocking.
The first case member has two opposite sides and includes a first cable guide at one of the two opposite sides of the first case member and a second cable guide at another of the two opposite sides of the first case member, with a first core housing provided between the opposite sides of the first case member. The second case member has two opposite sides and includes a third cable guide at one of the two opposite sides of the second case member and a fourth cable guide at another of the two opposite sides of the second case member, with a second core housing provided between the opposite sides of the second case member.
The first means for interlocking and the second means for interlocking secure the first and second case members, with the first means for interlocking securing the first and second case members partially, and the second means for interlocking securing the first and second case members entirely.
With this structure, when the first and second case members are secured either partially or entirely, the first and fourth cable guides face each other and form an aperture.
Similarly, when the first and second case members are secured either partially or entirely, the second and third cable guides face each other and form an aperture.
The case in the second mode comprises first and second case members each including a core housing. This structure allows a magnetic core to be housed entirely in said case by housing half of the magnetic core inside the first core housing of the first case member and housing the other half of the magnetic core into the second core housing of the second case member and by closing the first and second case members together. The noise absorber thus achieved can be mounted on a cable of an electronic device to absorb noise generated inside or outside the electronic device by guiding the cable through apertures formed by the first and fourth cable guides and the second and third cable guides, and the cable through passage of the magnetic core, thereby facilitating the cable insertion process.
The first means for interlocking latches the first and second case members partially and, as a result, apertures through which a cable can be inserted are formed. The noise absorber can be sold in a state in which the first and second case members are partially latched. Thus, when mounting the noise absorber onto a cable, the end user can insert a cable through the noise absorber in a state in which it was purchased.
In addition, the second means for interlocking latches the first and second case member entirely. This allows the end user to mount the noise absorber onto a cable with a high degree of reliability at a very slight angle of displacement relative to the partially latched state achieved by the first means for interlocking. Consequently, the noise absorber in the second mode can be mounted onto a cable quickly and easily.